Cooled heat exchange elements, such as the thermal skin proposed for hypersonic aircraft, are costly to design and manufacture due to the need to obtain both cooling and structural strength from the same element. In particular, the large panels necessary to produce the thermal skin for a large vehicle would be both labor intensive and quite costly to produce using present manufacturing techniques. Consequently, manufacturers of such heat exchange elements are seeking new ways of reducing the costs of producing cooled structural elements.
A typical structural panel shown in U.S. Pat. No. 3,739,843 to Haberski which discloses a structural panel formed from two sheets which have extended surface elements which are interposed to form a honeycomb structure. Unfortunately, the structural panel has no defined coolant flowpaths, and the cost associated with trying to assemble large structural panels using this design would likely be prohibitive. A typical example of a multiple panel heat exchanger is shown in U.S. Pat. No. 4,253,520 to Friedericy et al, which discloses a corrugated sheet sandwiched between two panels. The formed sheet must be welded or brazed to the panels to form individual flow passages, and the structural integrity of these welds is difficult to inspect.
What is needed is a method of making a tubular thermal structure having defined coolant flowpaths, which provides structural strength and is readily inspectable.